Intracranial atherosclerosis

Strong multi-functions based on conjugating chondroitin sulfate onto an amine-rich surface will direct the vascular cell fate for cardiovascular implanted devices

This research may support potential applications for surface modification of cardiovascular implants to achieve improved multi-functions.

Skeleton-based cerebrovascular quantitative analysis

Background

Cerebrovascular disease is the most common cause of death worldwide, with millions of deaths annually. Interest is increasing toward understanding the geometric factors that influence cerebrovascular diseases, such as stroke. Cerebrovascular shape analyses are essential for the diagnosis and pathological identification of these conditions. The current study aimed to provide a stable and consistent methodology for quantitative Circle of Willis (CoW) analysis and to identify geometric changes in this structure.

Method

An entire pipeline was designed with emphasis on automating each step. The stochastic segmentation was improved and volumetric data were obtained. The L1 medial axis method was applied to vessel volumetric data, which yielded a discrete skeleton dataset. A B-spline curve was used to fit the skeleton, and geometric values were proposed for a one-dimensional skeleton and radius. The calculations used to derive these values were illustrated in detail.

Result

In one example(No. 47 in the open dataset) all values for different branches of CoW were calculated. The anterior communicating artery(ACo) was the shortest vessel, with a length of 2.6mm. The range of the curvature of all vessels was (0.3, 0.9) ± (0.1, 1.4). The range of the torsion was (−12.4,0.8) ± (0, 48.7). The mean radius value range was (3.1, 1.5) ± (0.1, 0.7) mm, and the mean angle value range was (2.2, 2.9) ± (0, 0.2) mm. In addition to the torsion variance values in a few vessels, the variance values of all vessel characteristics remained near 1. The distribution of the radii of symmetrical posterior cerebral artery(PCA) and angle values of the symmetrical posterior communicating arteries(PCo) demonstrated a certain correlation between the corresponding values of symmetrical vessels on the CoW.

Conclusion

The data verified the stability of our methodology. Our method was appropriate for the analysis of large medical image datasets derived from the automated pipeline for populations. This method was applicable to other tubular organs, such as the large intestine and bile duct.

Electronic supplementary material

The online version of this article (doi:10.1186/s12880-016-0170-8) contains supplementary material, which is available to authorized users.

Co-existing intracranial and extracranial carotid artery atherosclerotic plaques and recurrent stroke risk: a three-dimensional multicontrast cardiovascular magnetic resonance study

BACKGROUND

As a systemic disease, atherosclerosis commonly affects intracranial and extracranial carotid arteries simultaneously which is defined as co-existing plaques. Previous studies demonstrated that co-existing atherosclerotic diseases are significantly associated with ischemic cerebrovascular events. The aim of this study was to investigate the characteristics of co-existing intracranial and extracranial carotid atherosclerotic plaques and their relationships with recurrent stroke by using 3D multi-contrast magnetic resonance (MR) vessel wall imaging.

METHODS

Patients with recent cerebrovascular symptoms in anterior circulation and at least one carotid plaque were recruited. All patients underwent cardiovascular magnetic resonance (CMR) for brain and intracranial and extracranial arteries. Presence/absence of atherosclerotic plaque at each arterial segment was identified. The maximum wall thickness (Max WT), length, stenosis of each plaque was measured. The presence/absence of calcification, lipid-rich necrotic core (LRNC), and intraplaque hemorrhage (IPH) was assessed. Cerebral old and acute infarcts in anterior circulation were evaluated.

RESULTS

Fifty-eight patients (mean age: 58.0 ± 8.5 years old, 34 males) were recruited. Of the 58 patients, co-existing intracranial and extracranial carotid artery plaques were found in 45 patients (77.6%), of which 7 (15.6%) had first time acute stroke and 26 (57.8%) had recurrent stroke. For these 33 patients with stroke, the number of intracranial plaques (OR = 11.26; 95% CI, 1.27-100; p = 0.030) and co-existing intracranial and extracranial carotid artery plaques (OR = 2.42; 95% CI, 1.04-5.64; p = 0.040) was significantly associated with recurrent stroke. After adjusting for traditional risk factors, the number of co-existing plaques was still significantly correlated with recurrent stroke (OR = 3.31; 95% CI, 1.09-10.08; p = 0.035). No correlations were found between recurrent stroke and Max WT, length, stenosis, and compositions of plaques.

CONCLUSIONS

Co-existing intracranial and extracranial carotid artery plaques are prevalent in symptomatic patients and the number of co-existing plaques is independently associated with the risk of recurrent stroke.

Treatment and imaging of intracranial atherosclerotic stenosis: current perspectives and future directions

BACKGROUND AND PURPOSE

Intracranial atherosclerosis is a common cause of stroke worldwide. It results in ischemic stroke due to different mechanisms including artery-to-artery embolism, in situ thrombo-occlusion, occlusion of perforating arteries, and hemodynamic failure. In this review, we present an overview of current treatment and imaging modalities in intracranial atherosclerotic stenosis.

METHODS

PubMed was searched for relevant articles in English that evaluated the treatment and imaging of intracranial atherosclerotic stenosis (ICAS).

RESULTS

Aggressive medical management, consisting of dual antiplatelet therapy and intensive risk factor management, is important in patients with ICAS because of a substantial risk of recurrent stroke, approximately 20% in the first year, in patients on aspirin or warfarin alone. Recent trials have suggested that, aggressive medical therapy results in better outcome as compared with intracranial stenting. However, the question remains what the optimal treatment strategy would be in patients with recurrent strokes in the setting of failed aggressive medical therapy. Moreover, controversy exists whether a subgroup of patients with symptomatic ICAS could benefit from intracranial stenting if selection is based on radiological evidence of hemodynamic failure. With regard to imaging, transcranial Doppler ultrasound and magnetic resonance angiography are useful screening tests for exclusion of ICAS, but need confirmation by other imaging modalities when stenosis is suggested. Computed tomography angiography has a high positive and negative predictive value for detection of intracranial luminal stenosis of 50% or higher, but performs worse than digital subtraction angiography with regard to establishing the exact degree of luminal stenosis. Novel imaging techniques including high-resolution CT and MRI better identify plaque characteristics than conventional imaging methods.

CONCLUSIONS

Currently, aggressive medical management remains the standard of care for patients with ICAS. Further research is needed to identify high-risk subgroups and to develop more effective treatments for ICAS patients.

A new clinically relevant model for intracranial atherosclerosis in rats

INTRODUCTION

Intracranial atherosclerotic stenosis (ICAS) is one of the most common causes of stroke worldwide and, in particular, has been implicated as a leading cause of recurrent ischemic stroke. We developed a new rat model to study intracranial atherosclerosis.

METHODS

Twelve-week-old male Sprague-Dawley rats were divided into a control (on a maintain diet) and a high-cholesterol group (on a daily 1% cholesterol diet) for up to 6 weeks. During the first two weeks, NG-nitro-L-arginine methylester (L-NAME, 3 mg/mL) was added to the drinking water in the high-cholesterol group to induce intimal changes making the rats susceptible to atherosclerosis. Blood lipids, including low-density lipoprotein (LDL), cholesterol (CHO), triglycerides (TG), and high-density lipoprotein (HDL), were measured after 3 and 6 weeks. Histological sections of the brains, including internal carotid artery (ICA), middle cerebral artery (MCA), and basilar artery (BA), were prepared to study intracranial artery morphometry and intimal thickening. The levels of CD68, an inflammatory marker, within the vessel walls as determined by immunohistochemistry were also measured.

RESULTS

The high-cholesterol diet increased the levels of classic blood markers of atherosclerosis, LDL, CHO, and TG as well as decreased HDL, which became progressively more intensive with time. Rats showed increased intimal thickening in the ICA, MCA, and BA. This protocol also increased the levels of CD68 immunoreactivity within the vessel walls.

CONCLUSIONS

A rat model of intracranial atherosclerosis was effectively developed by high-cholesterol diet and L-NAME administration. This clinically relevant model would be beneficial for studying ICAS.

The Ratio of Regulatory (FOXP3+) to Total (CD3+) T Cells Determined by Epigenetic Cell Counting and Cardiovascular Disease Risk: A Prospective Case-cohort Study in Non-diabetics

Background

Experimental and clinical evidence indicate that inflammatory processes in atherogenesis and the development of cardiovascular complications are promoted by a loss of regulatory T cell (Treg)-mediated immunological tolerance to plaque antigens. Yet, the association between alterations of systemic Treg frequency and cardiovascular disease incidence remains uncertain.

Methods

A nested case-cohort study was conducted within the European Prospective Investigation into Cancer and Nutrition (EPIC)-Heidelberg, comprising a random subcohort (n = 778) and primary cases of myocardial infarction (MI, n = 276) and ischemic stroke (n = 151). Pre-diagnostic FOXP3 + Treg and total CD3 + T-lymphocyte (tTL) frequencies in blood were measured by epigenetic-based, quantitative real-time PCR-assisted cell counting.

Results

Multivariate, Prentice-weighted Cox regression analyses revealed that lower Treg/tTL ratios were not associated with the risk of either MI (lowest vs. highest sex-specific quartile; hazard ratio: 0.72, 95% confidence interval: 0.46 to 1.13; P_trend = 0.51) or stroke (HR: 0.90, 95% CI: 0.51 to 1.60; P_trend = 0.78). There were no correlations of Treg/tTL ratios with C-reactive protein, HbA1c, and various lipid parameters.

Conclusions

Among middle-aged adults from the general population, imbalances in the relative frequency of Tregs within the total T cell compartment do not confer an increased risk of MI or stroke.

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We studied if peripheral immune tolerance, as reflected by regulatory (FOXP3+) to total (CD3+) T cells, relates to CVD risk.

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Epigenetic-based, qPCR assisted cell counting was used to quantify T cell subsets in long-term stored buffy coat samples.

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Lower Treg-mediated immune tolerance does not confer an increased risk of major CVD events.

Inflammation in the arterial intima plays a central role in atherosclerotic cardiovascular disease and may develop owing to autoimmune-like responses targeted against plaque antigens. While the ratio between regulatory T cells (Tregs) and effector T cells is thought to control such immune response outcomes and tolerance within the T cell compartment, we found no association with incidence of major CVD events. These findings imply that reduced systemic Treg frequencies observed in CVD patients follow rather than precede disease manifestation and that Treg variation within a physiological range may not – as previously reported - constitute a pre-disposing risk factor for CVD.

Interplay of Proximal Flow Confluence and Distal Flow Divergence in Patient-Specific Vertebrobasilar System

Approximately one-quarter of ischemic strokes involve the vertebrobasilar arterial system that includes the upstream flow confluence and downstream flow divergence. A patient-specific hemodynamic analysis is needed to understand the posterior circulation. The objective of this study is to determine the distribution of hemodynamic parameters in the vertebrobasilar system, based on computer tomography angiography images. Here, the interplay of upstream flow confluence and downstream flow divergence was hypothesized to be a determinant factor for the hemodynamic distribution in the vertebrobasilar system. A computational fluid dynamics model was used to compute the flow fields in patient-specific vertebrobasilar models (n = 6). The inlet and outlet boundary conditions were the aortic pressure waveform and flow resistances, respectively. A 50% reduction of total outlet area was found to induce a ten-fold increase in surface area ratio of low time-averaged wall shear stress (i.e., TAWSS ≤ 4 dynes/cm²). This study enhances our understanding of the posterior circulation associated with the incidence of atherosclerotic plaques.

Neurology Case Studies: Cerebrovascular Disease

This article discusses interesting vascular neurology cases including the management of intracranial stenosis, migraine headache and stroke risk, retinal artery occlusions associated with impaired hearing, intracranial occlusive disease, a heritable cause of stroke and vascular cognitive impairment, and an interesting clinico-neuroradiologic disorder associated with eclampsia.

High-resolution intracranial vessel wall MRI in an elderly asymptomatic population: comparison of 3T and 7T

Objectives

Several intracranial vessel wall sequences have been described in recent literature, with either 3-T or 7-T magnetic resonance imaging (MRI). In the current study, we compared 3-T and 7-T MRI in visualising both the intracranial arterial vessel wall and vessel wall lesions.

Methods

Twenty-one elderly asymptomatic volunteers were scanned by 3-T and 7-T MRI with an intracranial vessel wall sequence, both before and after contrast administration. Two raters scored image quality, and presence and characteristics of vessel wall lesions.

Results

Vessel wall visibility was equal or significantly better at 7 T for the studied arterial segments, even though there were more artefacts hampering assessment. The better visualisation of the vessel wall at 7 T was most prominent in the proximal anterior cerebral circulation and the posterior cerebral artery. In the studied elderly asymptomatic population, 48 vessel-wall lesions were identified at 3 T, of which 7 showed enhancement. At 7 T, 79 lesions were identified, of which 29 showed enhancement. Seventy-one percent of all 3-T lesions and 59 % of all 7-T lesions were also seen at the other field strength.

Conclusions

Despite the large variability in detected lesions at both field strengths, we believe 7-T MRI has the highest potential to identify the total burden of intracranial vessel wall lesions.

Key Points

• Intracranial vessel wall visibility was equal or significantly better at 7-T MRI

• Most vessel wall lesions in the cerebral arteries were found at 7-T MRI

• Many intracranial vessel wall lesions showed enhancement after contrast administration

• Large variability in detected intracranial vessel wall lesions at both field strengths

• Seven-tesla MRI has the highest potential to identify total burden of intracranial atherosclerosis

Electronic supplementary material

The online version of this article (doi:10.1007/s00330-016-4483-3) contains supplementary material, which is available to authorized users.

White Matter Hyperintensity Volume and Cerebral Perfusion in Older Individuals with Hypertension Using Arterial Spin-Labeling

BACKGROUND AND PURPOSE

White matter hyperintensities of presumed vascular origin in elderly patients with hypertension may be part of a general cerebral perfusion deficit, involving not only the white matter hyperintensities but also the surrounding normal-appearing white matter and gray matter. We aimed to study the relation between white matter hyperintensity volume and CBF and assess whether white matter hyperintensities are related to a general perfusion deficit.

MATERIALS AND METHODS

In 185 participants of the Prevention of Dementia by Intensive Vascular Care trial between 72 and 80 years of age with systolic hypertension, white matter hyperintensity volume and CBF were derived from 3D FLAIR and arterial spin-labeling MR imaging, respectively. We compared white matter hyperintensity CBF, normal-appearing white matter CBF, and GM CBF across quartiles of white matter hyperintensity volume and assessed the continuous relation between these CBF estimates and white matter hyperintensity volume by using linear regression.

RESULTS

Mean white matter hyperintensity CBF was markedly lower in higher quartiles of white matter hyperintensity volume, and white matter hyperintensity volume and white matter hyperintensity CBF were negatively related (standardized β = -0.248, P = .001) in linear regression. We found no difference in normal-appearing white matter or GM CBF across quartiles of white matter hyperintensity volume or any relation between white matter hyperintensity volume and normal-appearing white matter CBF (standardized β = -0.065, P = .643) or GM CBF (standardized β = -0.035, P = .382) in linear regression.

CONCLUSIONS

Higher white matter hyperintensity volume in elderly individuals with hypertension was associated with lower perfusion within white matter hyperintensities, but not with lower perfusion in the surrounding normal-appearing white matter or GM. These findings suggest that white matter hyperintensities in elderly individuals with hypertension relate to local microvascular alterations rather than a general cerebral perfusion deficit.

Atherosclerosis in the circle of Willis: Spatial differences in composition and in distribution of plaques

BACKGROUND AND AIMS

Intracranial atherosclerosis is one of the main causes of ischemic stroke. However, the characteristics of intracranial arteries and atherosclerosis have rarely been studied. Therefore, we systematically investigated atherosclerotic changes in all arteries of the Circle of Willis (CoW).

METHODS

Sixty-seven CoWs obtained at autopsy from randomly chosen hospital patients (mean age, 67.3 ± 12.5 years), of which a total of 1220 segments were collected from 22 sites. Atherosclerotic plaques were classified according to the revised American Heart Association classification and were related to local vessel characteristics, such as the presence of an external and internal elastic lamina and the elastic fibre density of the media.

RESULTS

181 out of the 1220 segments had advanced plaques (15%), which were mainly observed in large arteries such as the internal carotid, middle cerebral, basilar and vertebral artery. Only 11 out of 1220 segments (1%) showed complicated plaques (p < 0.001). Six of these were intraplaque hemorrhages (IPH) and observed only in patients who had cardiovascular-related events (p = 0.015). The frequency of characteristics such as the external elastic lamina and a high elastin fibre density in the media was most often associated with the vertebral artery. Only 3% (n = 33) of the CoW arteries contained calcification (p < 0.001), which were mostly observed in the vertebral artery (n = 13, 12%).

CONCLUSIONS

Advanced atherosclerotic plaques in the CoW are relatively scarce and mainly located in the 4 large arteries, and mostly characterized by an early and stable phenotype, a low calcific burden, and a low frequency of IPH.

The contemporary management of intracranial atherosclerotic disease

Intracranial atherosclerotic disease is the most common cause of cerebral vasculopathy and an important stroke etiology worldwide, with a higher prevalence in Asian, Hispanic and African ethnicities. Symptomatic intracranial atherosclerotic disease portends a recurrent stroke risk as high as 18% at one year. The key to secondary prevention is an understanding of the underlying stroke mechanism and aggressive control of conventional cardiovascular risks. Contemporary treatment includes antiplatelet therapy, optimal glycemic and blood pressure control, statin therapy and lifestyle modifications. For patients with high-grade (70-99%) symptomatic steno-occlusion, short-term dual antiplatelet therapy with aspirin and clopidogrel followed by life-long single antiplatelet therapy may reduce the recurrent risk. Current evidence does not advocate percutaneous transluminal angioplasty and stenting as an initial treatment. External counterpulsation, encephaloduroarteriosynangiosis and remote limb ischemic preconditioning are treatments under investigation. Future studies should aim at predicting patients prone to recurrence despite of medical therapies and testing the efficacy of emerging therapies.

Prevalence of Intracranial Atherosclerotic Stenosis Using High-Resolution Magnetic Resonance Angiography in the General Population: The Atherosclerosis Risk in Communities Study

BACKGROUND AND PURPOSE

Intracranial atherosclerotic stenosis (ICAS) is a common cause of stroke, but little is known about its epidemiology. We studied the prevalence of ICAS and its association with vascular risk factors using high-resolution magnetic resonance angiography in a US cardiovascular cohort.

METHODS

The Atherosclerosis Risk in Communities (ARIC) study recruited participants from 4 US communities from 1987 to 1989. Using stratified sampling, we selected 1980 participants from visit 5 (2011-2013) for high-resolution 3T-magnetic resonance angiography. All images were analyzed in a centralized laboratory, and ICAS was graded as: no stenosis, <50% stenosis, 50% to 69% stenosis, 70% to 99% stenosis, and complete occlusion. We calculated per-vessel and per-person prevalence of ICAS (weighted for n=6538 visit 5 participants) and also estimated the US prevalence. We used multivariable logistic regression to identify variables independently associated with ICAS.

RESULTS

Subjects who had an adequate magnetic resonance angiography (n=1765) were aged 67 to 90 years, 41% were men, 70% were white, and 29% were black. ICAS was prevalent in 31% of participants and 9% had ICAS ≥50%. Estimated US prevalence of ICAS ≥50% for 65 to 90 years old was 8% for whites and 12% for blacks. Older age, black race, higher systolic blood pressure, and higher low-density lipoprotein cholesterol levels were associated with increased odds of ICAS, whereas higher levels of high-density lipoprotein cholesterol and use of cholesterol-lowering medications were associated with decreased odds of ICAS. Body mass index and smoking were not associated with ICAS.

CONCLUSIONS

The prevalence of ICAS in older adults is high, and it could be a target for primary prevention of stroke and dementia in this population.

Quantitative Intracranial Atherosclerotic Plaque Characterization at 7T MRI: An Ex Vivo Study with Histologic Validation

BACKGROUND AND PURPOSE

In recent years, several high-resolution vessel wall MR imaging techniques have emerged for the characterization of intracranial atherosclerotic vessel wall lesions in vivo. However, a thorough validation of MR imaging results of intracranial plaques with histopathology is still lacking. The aim of this study was to characterize atherosclerotic plaque components in a quantitative manner by obtaining the MR signal characteristics (T1, T2, T2*, and proton density) at 7T in ex vivo circle of Willis specimens and using histopathology for validation.

MATERIALS AND METHODS

A multiparametric ultra-high-resolution quantitative MR imaging protocol was performed at 7T to identify the MR signal characteristics of different intracranial atherosclerotic plaque components, and using histopathology for validation. In total, 38 advanced plaques were matched between MR imaging and histology, and ROI analysis was performed on the identified tissue components.

RESULTS

Mean T1, T2, and T2* relaxation times and proton density values were significantly different between different tissue components. The quantitative T1 map showed the most differences among individual tissue components of intracranial plaques with significant differences in T1 values between lipid accumulation (T1 = 838 ± 167 ms), fibrous tissue (T1 = 583 ± 161 ms), fibrous cap (T1 = 481 ± 98 ms), calcifications (T1 = 314 ± 39 ms), and the intracranial arterial vessel wall (T1 = 436 ± 122 ms).

CONCLUSIONS

Different tissue components of advanced intracranial plaques have distinguishable imaging characteristics with ultra-high-resolution quantitative MR imaging at 7T. Based on this study, the most promising method for distinguishing intracranial plaque components is T1-weighted imaging.

Stroke due to large vessel atherosclerosis: Five new things

Purpose of review

Extracranial (EC) and intracranial (IC) large vessel atherosclerosis account for about 20% of ischemic stroke cases. In recent years, new treatments have emerged for treatment of both EC and IC disease.

Recent findings

The stroke rate in patients with carotid stenosis is decreasing with modern medical therapy. For patients with asymptomatic stenosis, the stroke rate is likely <1% per year. Some subsets of patients with symptomatic carotid disease benefit less from revascularization, and medical management can be considered in these patients. A second clinical trial has confirmed that aggressive medical management is the treatment of choice for IC atherosclerotic disease. Vessel wall imaging may be useful to define pathophysiology in patients with IC stenosis and could ultimately help tailor therapy, but further studies are needed. Medical therapy is preferred to stenting for patients with vertebral artery-origin stenosis.

Summary

Recent data and emerging concepts regarding large vessel atherosclerosis are provided.

Multifunctional Coating Based on Hyaluronic Acid and Dopamine Conjugate for Potential Application on Surface Modification of Cardiovascular Implanted Devices

Surface modification by conjugating biomolecules has been widely proved to enhance biocompatibility of cardiovascular implanted devices. Here, we aimed at developing a multifunctional surface that not only provides good hemocompatibility but also functions well in inducing desirable vascular cell-material interaction. In the present work, the multicoatings of hyaluronic acid (HA) and dopamine (PDA) were prepared onto 316L stainless steel (316L SS) via chemical conjugation (Michael addition, Schiff base reaction, and electrostatic adsorption). The results of platelet adhesion and activation and the whole blood tests indicated that the HA/PDA coatings obtained better hemocompatibility compared with the bare 316L SS and HA or PDA immobilized on 316L SS. The HA/PDA coatings also inhibited the proliferation of smooth muscle cells and adhesion/activation of macrophages effectively, whereas not all the HA/PDA coatings improved surface endothelialization rapidly and the effects of the multifunctional coatings on endothelial cell growth depend on the HA amounts (1.0, 2.0, and 5.0 mg/mL, labeled as PDA-HA-1, PDA-HA-2, and PDA-HA-5 respectively). Herein the PDA-HA-1 and PDA-HA-2 coatings were found to improve endothelial cell adhesion and proliferation significantly. The tissue compatibility of the HA/PDA coatings also depends on the HA amounts, and the PDA-HA-2 coating was proved to cause milder in vivo tissue response. Additionally, the mechanism of the HA molecular weight change and in vivo tissue response was also explored. These results effectively suggested that the HA/PDA coating might be promising when serving as a cardiovascular implanted device coating.

Multifunctional coating based on EPC-specific peptide and phospholipid polymers for potential applications in cardiovascular implants fate

Surface biofunctional modification of cardiovascular implants via the conjugation of biomolecules to prevent thrombosis and restenosis formation and to accelerate endothelialization has attracted considerable research interest.

Risk Factor Stratification for Intracranial Stenosis in Taiwanese Patients With Cervicocerebral Stenosis

BACKGROUND

Intracranial stenosis (ICS) is a major determinant of ischemic stroke in Asians. We determined the clinical significance of different risk factors and the role of ICS in Taiwanese patients with varied distributions of cervicocerebral stenosis.

METHODS AND RESULTS

Presence of extracranial carotid stenosis (ECS, ≥70%) and ICS (>50%) was examined in 13 539 patients using ultrasonography and magnetic resonance angiography, respectively. Seven hundred thirty-three patients with non-ECS/ICS (n=372), isolated ICS (n=112), isolated ECS (n=121), or combined ECS/ICS (CEIS, n=128) were selected. Prevalence of ischemic stroke in each group was compared, and risk factors for stenosis were determined. The area under the receiver operating characteristic curve for each risk factor was calculated. Prevalence of ischemic stroke was highest in patients with CEIS (odds ratio 15.86; P<0.001), followed in decreasing order by those with isolated ICS (odds ratio 7.16; P<0.001), isolated ECS (odds ratio 1.77; P=0.011), and non-ECS/ICS. Multivariate logistic regression analysis revealed that hypertension, coronary artery disease, and smoking were risk factors for isolated ECS; hypertension, diabetes mellitus, coronary artery disease, and smoking were risk factors for isolated ICS; and diabetes mellitus, coronary artery disease, and smoking were risk factors for CEIS. Smoking, diabetes mellitus, and coronary artery disease were the greatest contributors to CEIS, isolated ICS, and isolated ECS, respectively.

CONCLUSIONS

CEIS was associated with higher odds of ischemic stroke compared with isolated ICS and isolated ECS. Smoking and diabetes mellitus, major determinants of CEIS and isolated ICS, should be targeted in therapeutic strategies to reduce the risk of ischemic stroke.

Internal carotid artery stenting for intracranial atherosclerosis

Intracranial atherosclerotic disease is a significant cause of stroke in the United States. Much like coronary atherosclerosis, this disease leads to arterial stenosis secondary to the buildup of lipid-based plaques in intracranial vessels. Ischemic stroke may occur following thromboembolic events near the site of stenosis or from watershed ischemia secondary to cerebral hypoperfusion. While this disease has been treated with intracranial angioplasty and stenting and cerebrovascular bypass surgery, the current literature supports aggressive medical management with dual antiplatelet therapy, treatment of comorbidities such as hypertension, diabetes, and hyperlipidemia, and lifestyle modification. Intracranial angioplasty and stenting is reserved for cases of medical failure.

Relationship between visible branch arteries distal to the stenosis on magnetic resonance angiography and stroke recurrence in patients with severe middle cerebral artery trunk stenosis: a one-year follow up study

Background

To evaluate the relationship between the flow signal intensity of branch arteries distal to the stenosis on 3-dimensional (3D) time-of-flight (TOF) magnetic resonance angiography (MRA) and the risk of stroke recurrence in patients with severe middle cerebral artery (MCA) trunk stenosis.

Methods

We prospectively recruited 153 patients (mean age 62.9 ± 13.0 years, 106 males) with a first ischemic stroke or transient ischemic attack caused by a severe MCA trunk stenosis (70 % to 99 %) confirmed by 3D TOF MRA and followed them for one year to determine the stroke recurrence. The MCA branch signal intensity distal to the site of stenosis on 3D TOF MRA was classified as either good (grade A) or poor [mild reduction (grade B) or severe reduction (grade C)] according to the extent to which the MCA could be visualized. The patients were divided into groups A (35), B (58), or C (60) based on the MRA grading of the MCA branch signal intensity distal to the site of stenosis.

Results

Poor MCA branch signal intensity was associated with internal border-zone infarction (p < 0.05). The risk of stroke recurrence in the ipsilateral MCA in the first year was 18.3 %. The 1-year cumulative incidence of recurrence was higher in the patients in group C (30 %) than in groups B (12.1 %) or A (8.6 %) (Log rank, p = 0.007). Multivariate analyses via Cox proportional hazard regression demonstrated that only a grade C classification of the signal intensity of the MCA branches was an independent predictor of stroke recurrence in the ipsilateral MCA (hazard ratio = 3.0, 95 % confidence interval = 1.3-7.4, p = 0.014).

Conclusions

This study demonstrated that MCA branch signal intensity as assessed via 3D TOF MRA may be a useful and simple tool to stratify the risk of stroke recurrence in patients with severe MCA trunk stenosis.

The Pathophysiological Mechanism Is an Independent Predictor of Long-Term Outcome in Stroke Patients with Large Vessel Atherosclerosis

BACKGROUND

Etiopathological mechanisms underlying ischemic stroke play a crucial role in long-term prognosis. We aimed to investigate the association between the mechanism of stroke due to large vessel disease, and long-term outcome.

METHODS

All consecutive patients registered in the Athens Stroke Registry with atherosclerotic stroke between 1993 and 2010 were included in the analysis. The patients were subdivided into 3 groups according to the presumed underlying mechanism: low-flow infarcts, artery-to-artery embolism, and intrinsic atherosclerosis. They were followed up for up to 10 years or until death. The end points of the study were 10-year all-cause mortality, stroke recurrence, and composite cardiovascular events.

RESULTS

Five hundred two patients were classified as follows: 156 (31%) as low-flow (watershed) strokes, 256 (51%) as artery-to-artery embolic strokes, and 90 (18%) as intrinsic atherosclerotic strokes. The cumulative probability of 10-year mortality rate was similar between groups of patients with different stroke mechanisms: 49.9% (95% confidence interval [CI], 38.5-61.3) for patients with low-flow mechanism, 47.6% (95% CI, 39.4-55.8) for patients with artery-to-artery embolism, and 48.5% (95% CI, 34.0-63.0) for patients with intrinsic atherosclerosis. Patients in the intrinsic atherosclerosis group had significantly higher risks of recurrence (adjusted hazard ratio [HR] = 2.1; 95% CI, 1.19-3.73) compared with those in the artery-to-artery embolism group. Moreover, patients in the intrinsic atherosclerosis and low-flow groups had significantly higher risks of composite cardiovascular events compared with those in the artery-to-artery embolism group (adjusted HR = 1.94; 95% CI, 1.26-3.00; and adjusted HR = 1.64; 95% CI, 1.13-2.38, respectively).

CONCLUSION

Low-flow and intrinsic atherosclerosis strokes are associated with a high risk for future cardiovascular events and stroke recurrence. However, long-term mortality is similar across different subgroups.

Stenting in Intracranial Stenosis: Current Controversies and Future Directions

Angioplasty and stenting for intracranial atherosclerotic stenosis (ICAS) are a last resort for patients with high-grade intracranial stenosis with multiple ischemic events unresponsive to medical therapy. Medical management, consisting of aggressive risk factor control and dual antiplatelet therapy, is superior to angioplasty and stenting for the prevention of future stroke. Future studies of angioplasty and stenting in this population are important, as the stroke risk on medical therapy is 12 % at 1 year and post-procedure stroke rates are similar to rates with medical treatment. There are many issues that will need to be resolved for stenting to offer any benefit, however. Procedural risks of hemorrhagic and ischemic stroke are unacceptably high. High-risk subgroups, potentially based on hemodynamic factors, will need to be identified for future interventional trials. Nevertheless, it is still reasonable to consider angioplasty and stenting for selected patients with multiple recurrent events despite aggressive medical management, but benefits are unclear at this time.

Evaluation of 3D multi-contrast joint intra- and extracranial vessel wall cardiovascular magnetic resonance

BACKGROUND

Multi-contrast vessel wall cardiovascular magnetic resonance (CMR) has demonstrated its capability for atherosclerotic plaque morphology measurement and component characterization in different vasculatures. However, limited coverage and partial volume effect with conventional two-dimensional (2D) techniques might cause lesion underestimation. The aim of this work is to evaluate the performance in a) blood suppression and b) vessel wall delineation of three-dimensional (3D) multi-contrast joint intra- and extracranial vessel wall imaging at 3T.

METHODS

Three multi-contrast 3D black blood (BB) sequences with T1, T2 and heavy T1 weighting and a custom designed 36-channel neurovascular coil covering the entire intra- and extracranial vasculature have been used and investigated in this study. Two healthy subjects were recruited for sequence parameter optimization and twenty-five patients were consecutively scanned for image quality and blood suppression assessment. Qualitative image scores of vessel wall delineation as well as quantitative Signal-to-Noise Ratio (SNR) and Contrast-to-Noise Ratio (CNR) were evaluated at five typical locations ranging from common carotid arteries to middle cerebral arteries.

RESULTS

The 3D multi-contrast images acquired within 15mins allowed the vessel wall visualization with 0.8 mm isotropic spatial resolution covering intra- and extracranial segments. Quantitative wall and lumen SNR measurements for each sequence showed effective blood suppression at all selected locations (P < 0.0001). Although the wall-lumen CNR varied across measured locations, each sequence provided good or adequate image quality in both intra- and extracranial segments.

CONCLUSIONS

The proposed 3D multi-contrast vessel wall technique provides isotropic resolution and time efficient solution for joint intra- and extracranial vessel wall CMR.

Negative Susceptibility Vessel Sign and Underlying Intracranial Atherosclerotic Stenosis in Acute Middle Cerebral Artery Occlusion

BACKGROUND AND PURPOSE

The role of MR imaging in predicting underlying intracranial atherosclerotic stenosis before endovascular stroke therapy has not been studied. Our aim was to determine the diagnostic value of the negative susceptibility vessel sign on T2*-weighted gradient-echo MR imaging for predicting underlying intracranial atherosclerotic stenosis in patients with acute MCA occlusion.

MATERIALS AND METHODS

Ninety-one consecutive patients with acute stroke because of MCA occlusion underwent gradient-echo MR imaging and MRA before endovascular therapy. The negative susceptibility vessel sign was defined as an absence of a hypointense signal change within the occluded MCA on gradient-echo imaging. Underlying intracranial atherosclerotic stenosis was determined by conventional angiography. The sensitivity, specificity, predictive values, and accuracy of the negative susceptibility vessel sign for predicting the presence of underlying intracranial atherosclerotic stenosis were assessed.

RESULTS

The negative susceptibility vessel sign was identified in 42 (46.1%) of 91 patients, and 18 (19.8%) patients had an underlying intracranial atherosclerotic stenosis responsible for acute ischemic symptoms. The negative susceptibility vessel sign was more frequently observed in patients with intracranial atherosclerotic stenosis than in those without it (100% versus 32.9%, P < .001). In the prediction of an underlying intracranial atherosclerotic stenosis, the negative susceptibility vessel sign had 100% sensitivity, 67.1% specificity, 42.9% positive predictive value, 100% negative predictive value, and an accuracy of 73.6%.

CONCLUSIONS

The negative susceptibility vessel sign on gradient-echo MR imaging is a sensitive marker with a high negative predictive value for the presence of an underlying intracranial atherosclerotic stenosis in patients with acute ischemic stroke because of MCA occlusions. The susceptibility vessel sign can be used in decision-making when performing subsequent endovascular revascularization therapy in patients with acute MCA occlusions.

An evidence-based update on the pharmacological activities and possible molecular targets of Lycium barbarum polysaccharides

Lycium barbarum berries, also named wolfberry, Fructus lycii, and Goji berries, have been used in the People’s Republic of China and other Asian countries for more than 2,000 years as a traditional medicinal herb and food supplement. L. barbarum polysaccharides (LBPs) are the primary active components of L. barbarum berries and have been reported to possess a wide array of pharmacological activities. Herein, we update our knowledge on the main pharmacological activities and possible molecular targets of LBPs. Several clinical studies in healthy subjects show that consumption of wolfberry juice improves general wellbeing and immune functions. LBPs are reported to have antioxidative and antiaging properties in different models. LBPs show antitumor activities against various types of cancer cells and inhibit tumor growth in nude mice through induction of apoptosis and cell cycle arrest. LBPs may potentiate the efficacy of lymphokine activated killer/interleukin-2 combination therapy in cancer patients. LBPs exhibit significant hypoglycemic effects and insulin-sensitizing activity by increasing glucose metabolism and insulin secretion and promoting pancreatic β-cell proliferation. They protect retinal ganglion cells in experimental models of glaucoma. LBPs protect the liver from injuries due to exposure to toxic chemicals or other insults. They also show potent immunoenhancing activities in vitro and in vivo. Furthermore, LBPs protect against neuronal injury and loss induced by β-amyloid peptide, glutamate excitotoxicity, ischemic/reperfusion, and other neurotoxic insults. LBPs ameliorate the symptoms of mice with Alzheimer’s disease and enhance neurogenesis in the hippocampus and subventricular zone, improving learning and memory abilities. They reduce irradiation- or chemotherapy-induced organ toxicities. LBPs are beneficial to male reproduction by increasing the quality, quantity, and motility of sperm, improving sexual performance, and protecting the testis against toxic insults. Moreover, LBPs exhibit hypolipidemic, cardioprotective, antiviral, and antiinflammatory activities. There is increasing evidence from preclinical and clinical studies supporting the therapeutic and health-promoting effects of LBPs, but further mechanistic and clinical studies are warranted to establish the dose–response relationships and safety profiles of LBPs.

Imaging the intracranial atherosclerotic vessel wall using 7T MRI: initial comparison with histopathology

BACKGROUND AND PURPOSE

Several studies have attempted to characterize intracranial atherosclerotic plaques by using MR imaging sequences. However, dedicated validation of these sequences with histology has not yet been performed. The current study assessed the ability of ultra-high-resolution 7T MR imaging sequences with different image contrast weightings to image plaque components, by using histology as criterion standard.

MATERIALS AND METHODS

Five specimens of the circle of Wills were imaged at 7T with 0.11 × 0.11 mm in-plane-resolution proton attenuation-, T1-, T2-, and T2*-weighted sequences (through-plane resolution, 0.11-1 mm). Tissue samples from 13 fiducial-marked locations (per specimen) on MR imaging underwent histologic processing and atherosclerotic plaque classification. Reconstructed MR images were matched with histologic sections at corresponding locations.

RESULTS

Forty-four samples were available for subsequent evaluation of agreement or disagreement between plaque components and image contrast differences. Of samples, 52.3% (n = 23) showed no image contrast heterogeneity; this group comprised solely no lesions or early lesions. Of samples, 25.0% (n = 11, mostly advanced lesions) showed good correlation between the spatial organization of MR imaging heterogeneities and plaque components. Areas of foamy macrophages were generally seen as proton attenuation-, T2-, and T2*- hypointense areas, while areas of increased collagen content showed more ambiguous signal intensities. Five samples showed image-contrast heterogeneity without corresponding plaque components on histology; 5 other samples showed contrast heterogeneity based on intima-media artifacts.

CONCLUSIONS

MR imaging at 7T has the image contrast capable of identifying both focal intracranial vessel wall thickening and distinguishing areas of different signal intensities spatially corresponding to plaque components within more advanced atherosclerotic plaques.

Flow-independent dynamics in aneurysms: intra-aneurysm pressure measurements following complete flow cessation in internal carotid artery aneurysms

PURPOSE

To determine if complete flow obliteration by covered stents reduces intra-aneurysm pressures in internal carotid artery (ICA) aneurysms.

METHODS

A single lumen microcatheter was placed into the aneurysm sac prior to covered stent deployment in 3 patients and connected to a pressure monitoring system. The intra-aneurysm pressure was continuously monitored, and readings were recorded prior to and immediately after stent deployment and at 5-minute intervals up to 20 minutes after stent placement. Complete occlusion of flow into the aneurysms was confirmed by carotid angiography.

RESULTS

There was no change in mean pressure within the aneurysm before and immediately after stent placement (80 mmHg) in any patient, nor was there a change in waveform of the intra-aneurysm pressure recording. The average of intra-aneurysm pressures among the 3 patients was higher (99 mmHg) at 10 and 15 minutes after stent placement. In 2 patients, the microcatheter was retracted into the parent arterial lumen; no difference in pressure was noted.

CONCLUSION

Our observations suggest no change in the pressures within the aneurysm after complete flow cessation (flow-independent). These findings may assist clinicians in better understanding aneurysm hemodynamics and rupture after covered stent deployment.

Top 10 cardiovascular therapies and interventions for the next decade

Cardiovascular disease (CVD) has become the most-common cause of death worldwide. The Western lifestyle does not promote healthy living, and the consequences are most devastating when social inequalities are combined with economic factors and population growth. The expansion of poor nutritional habits, obesity, and associated conditions (such as diabetes mellitus, hypertension, physical inactivity, and advancing age) are major risk factors for developing CVD and are increasing in prevalence. Individuals in low-income and middle-income countries are undergoing a major shift in cardiovascular risk factors as they adopt Western lifestyles, a phenomenon that is hastened by industrialization, urbanization, and globalization. In this Perspectives article, I predict the 10 most-promising advances in cardiovascular therapies and interventions. Our improved understanding of CVD might help us, during the next decade, to achieve a transition from treating complex disease to promoting global cardiovascular health.

Ischemic posterior circulation stroke: a review of anatomy, clinical presentations, diagnosis, and current management

Posterior circulation strokes represent approximately 20% of all ischemic strokes (1, 2). In contrast to the anterior circulation, several differences in presenting symptoms, clinical evaluation, diagnostic testing, and management strategy exist presenting a challenge to the treating physician. This review will discuss the anatomical, etiological, and clinical classification of PC strokes, identify diagnostic pitfalls, and overview current therapeutic regimens.